Make MethodProbes use MethodHandles over reflection (HZ-3024) (#2…

…5279)

When accessing the data provided by `MethodProbe`s, currently core Java
reflection is used.

I've replaced this with
[`MethodHandle`s](https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/invoke/MethodHandle.html):

- with a `MethodHandle` it's possible to directly access a primitive,
without boxing/unboxing - reducing object creation (and therefore
garbage collection overhead)
- it allows the handle to be constructed once and used over and over
again allowing it to be more efficient

**Benchmarks:**
I benchmarked
([`MethodProbeBenchmark`](hazelcast/internal-benchmarks#40))
the improvement made to a the usage of a `MethodProbe`:

| Access Type | Method Type | ns/op | GC Alloc Rate (MB/s) | GC Alloc
Rate Norm (b/op) | GC Count | GC Time (ms) |
| ------------- | ------------- | ------------- | ------------- |
------------- | ------------- | ------------- |
| Reflection | `long` primitive | 6.8 | 3368 | 24 | 56 | 25 |
| `MethodHandle` | `long` primitive | 4.3 | 0.05 | 0 | 0 | 0 |
| Reflection | `Long` Object | 6.7 | 3419 | 24 | 62 | 23 |
| `MethodHandle` | `Long` Object | 2.1 | 0.05 | 0 | 0 | 0 |

The improvements are:
- faster execution time
- an order of magnitude more efficient in terms of garbage collection

This benchmark includes the overhead of the method operation itself - so
is reflective of the real-world observable performance improvement,
rather than a theoretical comparison of the two implementations.

More information on the implementation can be found in the Javadoc of
[`MethodProbe`](https://github.com/hazelcast/hazelcast/blob/a00165c95bea4641977ae2eaf58aadd5ac42a779/hazelcast/src/main/java/com/hazelcast/internal/metrics/impl/MethodProbe.java).

**Summary of Changes**

- Made `MethodProbe` use `MethodHandle`s
- Migrated static `int` constants in `ProbeUtils` to `ProbeType` `enum`
  - Allows properties to be added
  - Allows static methods to be moved into the object
  - Tidy `flatten`ing logic to avoid a `List.contains` iteration
- Updated `FieldProbe` to suit refactoring

Fixes [#25244](#25244)

hazelcast/src/main/java/com/hazelcast/internal/metrics/DoubleProbeFunction.java

@@ -17,7 +17,7 @@
 package com.hazelcast.internal.metrics;
 
 /**
- * A {@link ProbeFunction} that provides a double value and can be used to
+ * A {@link ProbeFunction} that provides a {@link double} value and can be used to
  * create a probe using {@link MetricsRegistry#registerStaticProbe(Object, String, ProbeLevel, LongProbeFunction)}
  *
  * @param <S> the type of the source object.
@@ -26,8 +26,6 @@
 public interface DoubleProbeFunction<S> extends ProbeFunction {
 
     /**
-     * Gets the current value of the source object.
-     *
      * @param source the source object.
      * @return the current value of the source object.
      * @throws Exception if something fails while getting the value.

hazelcast/src/main/java/com/hazelcast/internal/metrics/LongProbeFunction.java

@@ -17,7 +17,7 @@
 package com.hazelcast.internal.metrics;
 
 /**
- * A {@link ProbeFunction} that provides a long value and can be used to create
+ * A {@link ProbeFunction} that provides a {@link long} value and can be used to create
  * a probe using {@link MetricsRegistry#registerStaticProbe(Object, String, ProbeLevel, LongProbeFunction)}
  *
  * @param <S> the type of the source object.
@@ -26,8 +26,6 @@
 public interface LongProbeFunction<S> extends ProbeFunction {
 
     /**
-     * Gets the current value of the source object as a long.
-     *
      * @param source the source object.
      * @return the current value of the source object.
      * @throws Exception if something fails while getting the value.

hazelcast/src/main/java/com/hazelcast/internal/metrics/impl/FieldProbe.java

@@ -16,6 +16,9 @@
 
 package com.hazelcast.internal.metrics.impl;
 
+import static com.hazelcast.internal.metrics.impl.ProbeType.getType;
+import static java.lang.String.format;
+
 import com.hazelcast.internal.metrics.DoubleProbeFunction;
 import com.hazelcast.internal.metrics.LongProbeFunction;
 import com.hazelcast.internal.metrics.MetricDescriptor;
@@ -28,30 +31,18 @@
 import java.util.Map;
 import java.util.concurrent.Semaphore;
 
-import static com.hazelcast.internal.metrics.impl.ProbeUtils.TYPE_COLLECTION;
-import static com.hazelcast.internal.metrics.impl.ProbeUtils.TYPE_COUNTER;
-import static com.hazelcast.internal.metrics.impl.ProbeUtils.TYPE_DOUBLE_NUMBER;
-import static com.hazelcast.internal.metrics.impl.ProbeUtils.TYPE_DOUBLE_PRIMITIVE;
-import static com.hazelcast.internal.metrics.impl.ProbeUtils.TYPE_LONG_NUMBER;
-import static com.hazelcast.internal.metrics.impl.ProbeUtils.TYPE_MAP;
-import static com.hazelcast.internal.metrics.impl.ProbeUtils.TYPE_PRIMITIVE_LONG;
-import static com.hazelcast.internal.metrics.impl.ProbeUtils.TYPE_SEMAPHORE;
-import static com.hazelcast.internal.metrics.impl.ProbeUtils.getType;
-import static com.hazelcast.internal.metrics.impl.ProbeUtils.isDouble;
-import static java.lang.String.format;
-
 /**
  * A FieldProbe is a {@link ProbeFunction} that reads out a field that is annotated with {@link Probe}.
  */
 abstract class FieldProbe implements ProbeFunction {
 
     final CachedProbe probe;
     final Field field;
-    final int type;
+    final ProbeType type;
     final SourceMetadata sourceMetadata;
     final String probeName;
 
-    FieldProbe(Field field, Probe probe, int type, SourceMetadata sourceMetadata) {
+    FieldProbe(Field field, Probe probe, ProbeType type, SourceMetadata sourceMetadata) {
         this.field = field;
         this.probe = new CachedProbe(probe);
         this.type = type;
@@ -79,28 +70,30 @@ String getProbeName() {
     }
 
     static <S> FieldProbe createFieldProbe(Field field, Probe probe, SourceMetadata sourceMetadata) {
-        int type = getType(field.getType());
-        if (type == -1) {
+        ProbeType type = getType(field.getType());
+        if (type == null) {
             throw new IllegalArgumentException(format("@Probe field '%s' is of an unhandled type", field));
         }
 
-        if (isDouble(type)) {
+        if (type.getMapsTo() == double.class) {
             return new DoubleFieldProbe<S>(field, probe, type, sourceMetadata);
-        } else {
+        } else if (type.getMapsTo() == long.class) {
             return new LongFieldProbe<S>(field, probe, type, sourceMetadata);
+        } else {
+            throw new IllegalArgumentException(type.toString());
         }
     }
 
     static class LongFieldProbe<S> extends FieldProbe implements LongProbeFunction<S> {
 
-        LongFieldProbe(Field field, Probe probe, int type, SourceMetadata sourceMetadata) {
+        LongFieldProbe(Field field, Probe probe, ProbeType type, SourceMetadata sourceMetadata) {
             super(field, probe, type, sourceMetadata);
         }
 
         @Override
         public long get(S source) throws Exception {
             switch (type) {
-                case TYPE_PRIMITIVE_LONG:
+                case TYPE_LONG_PRIMITIVE:
                     return field.getLong(source);
                 case TYPE_LONG_NUMBER:
                     Number longNumber = (Number) field.get(source);
@@ -125,7 +118,7 @@ public long get(S source) throws Exception {
 
     static class DoubleFieldProbe<S> extends FieldProbe implements DoubleProbeFunction<S> {
 
-        DoubleFieldProbe(Field field, Probe probe, int type, SourceMetadata sourceMetadata) {
+        DoubleFieldProbe(Field field, Probe probe, ProbeType type, SourceMetadata sourceMetadata) {
             super(field, probe, type, sourceMetadata);
         }